KR20030004527A - Dry cleaning/ashing method and apparatus - Google Patents

Abstract

PURPOSE: A method and an apparatus for performing a dry cleaning/ashing process are provided to remove effectively organic materials from a surface of a substrate by promoting generation of oxygen radicals and restraining generation of ozone. CONSTITUTION: A discharge tube(110) is formed with an earth electrode(111a) including a dielectric(112), a working electrode(111b) including a heating plate(113) a nozzle(114) for injecting gases, a pressure gauge(118), and a gas exhaust valve(119). A substrate(117) is loaded on the heating plate(113). The electric power is applied between the earth electrode(111a) and the working electrode(111b) by a power supply portion(120). A reactive gas supply portion is formed with a reactive gas tank(131), a reactive gas valve(132), a flow rate controller(133), a mixing valve(146), a valve(147), and a connection tube. A carrier gas supply portion is formed with a carrier gas tank(141), a carrier gas valve(142), a flow rate controller(143), a mixing valve(146), a valve(147), and a connecting tube. An additional gas supply portion is formed with a barrel(150) for storing sources(152) and a connecting tube. A thermal sensor(153) is installed at the barrel(150). The first heating portion(151) is installed at the barrel(150) in order to heat the sources(152). The second heating portion(156) is used for heating the connecting tube.

Description

Dry cleaning / ashing method and apparatus

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a cleaning / ashing technique for large substrates (substrate or pannel) such as PDPs and LCDs, and more particularly, to a dry cleaning / ashing method and apparatus for semiconductor or glass panels using atmospheric pressure plasma discharge techniques. .

In general, semiconductor devices are manufactured through a number of processes, and the surface of large flat panel display devices such as silicon wafers, glass panels, PDPs, and LCDs may be impurities. As it is contaminated, a cleaning process to remove this impurity is essential.

The cleaning method of a semiconductor substrate is largely classified into a wet chemical method, a dry method, a vapor phase method, and the like. Traditional wafer cleaning methods were mostly chemical wet methods using hydrogen peroxide solution, but are gradually changed to dry or gas phase methods due to the consumption of many chemicals, the disposal of these materials, and the incompatibilities in developing manufacturing processes.

Impurities present on the surface of the substrate consist of a film, individual particles or agglomerates, adsorbed gases, etc., which have material properties such as atoms, ions, and molecules. Molecular impurities mainly consist of condensed organic gases from lubricating oils, photosensitizers, solvent residues, organic compounds from DI water (Deionized water) or plastic containers, metal oxides or hydroxides. Most of the ionic impurities come from inorganic compounds that are physically adsorbed or chemically bound such as Na, F, Cl ions, etc., and the atomic impurities are chemically and electrically formed on the semiconductor surface from HF solution containing gold or copper. It is attached.

As a technique for cleaning such impurities, the RCA method is a wet cleaning method combining ammonia hydrogen peroxide solution, hydrofluoric acid solution, and hydrochloric acid peroxide solution, and conventional dry cleaning method contaminates the surface of a substrate by chlorine radicals generated by ultraviolet (UV) irradiation. It is a method of evaporating and removing metal with metal chloride. In other words, the conventional cleaning technique is mainly a method of wet cleaning, using a large amount of aqueous and hazardous solutions to treat the surface of the target object or to activate ozone by ultraviolet (Ultra-Violet), such as UV-O ₃ cleaning Or a method of using an oxygen plasma in a vacuum.

However, the wet method of the conventional cleaning method has problems due to the discharge of environmental pollutants, the increase of the apparatus, the increase in maintenance costs, etc., the method using UV / O ₃ takes a long time to process, ultraviolet (UV) ) There is a problem that the maintenance cost of the equipment is high because the lamp life is short and the price is high. In addition, dry technologies such as vacuum plasma treatment using plasma and atmospheric dielectric barrier discharge treatment have superior advantages over wet or UV / O ₃ technologies. However, the technique using vacuum plasma is limited in size and expensive. Atmospheric pressure plasma technology requires an abnormal discharge shape such as a streamer or an arc in which a local discharge current is concentrated without generating a uniform plasma due to the characteristics of discharging and discharging the reactor using a high voltage. This occurs, a large amount of ozone harmful to the human body is generated, there is a problem that the reactivity is also lowered. In particular, when cleaning a large flat plate such as a glass panel such as PDP or LCD, or a transparent polymer for building materials, such a local abnormal discharge phenomenon and the generation of ozone (O ₃ ) is a big problem that inhibits effective dry cleaning. Can be.

The present invention has been proposed to solve the above problems, dry cleaning / ashing method that can promote the generation of oxygen radicals, which are chemically active species, to suppress the generation of harmful ozone in order to efficiently remove the organic substances on the substrate surface And to provide a device.

1 is a schematic configuration diagram showing a dry cleaning / ashing device according to the present invention;

2 is another example of a dry cleaning / ashing device according to the present invention;

3 is a flow chart showing the procedure of the dry cleaning / ashing method according to the present invention.

* Explanation of symbols for main parts of the drawings

110: room temperature plasma discharge tube 111a, 111b: electrode

112: dielectric 113: heating plate

114: nozzle 115: pressure gauge

117: substrate 118: discharge pipe

119: discharge valve 120: power supply

131: reaction gas cylinder 132: carrier gas cylinder

132, 142, 144, 147, 154, 119: Valve 146: Mixing valve

151,156 heating device 150 barrel

In order to achieve the above object, the method of the present invention, in the substrate cleaning / ashing method using an atmospheric pressure plasma discharge, discharge by injecting any one of the group consisting of water vapor, alcohol, acetone, hydrogen peroxide into the discharge tube together with the reaction gas OH radicals are generated to clean / ash semiconductor substrates, glass panels, and transparent polymers. In addition, according to the present invention, there is a method of generating steam using a method of directly injecting steam generated by using a boiler into a discharge tube or by bubbling using a carrier gas.

In addition, in order to achieve the above object, the apparatus of the present invention can mount a substrate for cleaning, and when the AC voltage of a predetermined frequency is applied to both electrodes with a dielectric therebetween, a normal pressure for generating plasma by discharge. Plasma discharge tube; Reaction gas injection means for injecting reaction gas into the plasma discharge tube; Carrier gas injection means for injecting a carrier gas for transporting gases into the plasma discharge tube; Characterized in that the addition gas injection means for injecting the additional gas into the plasma discharge tube. Here, the additive gas injection means is configured to inject any one of DI water, acetone, alcohol, hydrogen peroxide by bubbling using the carrier gas, or is configured to directly inject the steam of boiling water by the boiler to the discharge tube. have.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

First, briefly explaining the concept of the present invention, removing the organic material on the surface of the substrate in the cleaning process is to break the bond between the "C" and "H" forming the organic material by external applied energy, CO ₂ , or H ₂ It means to discharge to the outside in the form of O. This is equivalent to oxidizing the organic material on the substrate surface. Chemically active species (radical) for oxidizing organic materials include a variety of fluorine compounds, -OH, -O, O ₃ , H ₂ O ₂ . Among these, fluorine compounds and -OH are known to have a particularly high oxidizing potential. Therefore, the introduction of such oxidizing functional groups on the surface of the substrate during the cleaning or ashing process at high pressure using plasma can increase the processing time and efficiency more than ten times compared to using oxygen gas or ozone. It is possible to obtain an effect of converting harmful gases such as O ₃ generated by the reaction into highly reactive and non-hazardous oxygen (O) radicals.

That is, in the conventional cleaning process using plasma, oxygen plasma was used. In this case, only oxidation on the surface of the substrate by relatively inferior ozone formed by activated oxygen atoms or discharges, as shown in Equation 1 below. Since it is possible to limit the degree of cleaning or ashing, there is also a problem that harmful ozone gas is emitted in the case of open systems.

By the way, the present invention is to introduce a more powerful oxidant to shorten the treatment time and solve the problem of ozone generation. That is, in general, as the oxidizing agent, -OH, -O, O ₃ , H ₂ O ₂ and the like are used. Among them, since the OH radical has the strongest oxidizing power, introducing this functional group to the surface of the substrate as much as possible increases the cleaning efficiency. It's the best way. In addition, since the OH functional group inhibits the ozone generation reaction when oxygen is decomposed and generates oxygen atoms, the OH functional group has a great effect on the cleaning efficiency.

In the cleaning procedure according to the present invention, as shown in FIG. 3, after the substrate is installed in the discharge tube, the substrate is heated to improve reactivity, and an additive gas is generated by bubbling (S1 to S3). The generated additive gas is mixed with the reaction gas and injected into the discharge tube, and OH radicals are generated by the discharge. Accordingly, strong cleaning of the substrate is performed while suppressing ozone generation (S4 to S6).

As a method for generating OH functional groups, first, a method of bubbling DI water (Deionized water) with a carrier gas, second, a method of directly spraying H ₂ O of 100 ° C. or more in the gaseous phase, and third, alcohol or acetone And the fourth method using hydrogen peroxide.

First embodiment

As shown in FIG. 1, a system for bubbling DI water into a carrier gas in dry cleaning using an atmospheric pressure dielectric barrier barrier discharge includes a discharge tube 110, a reaction gas supply part, a carrier gas supply part, and an additive gas supply part.

The discharge tube 110 includes a ground electrode 111a having the dielectric 112 attached thereto, a working electrode 111b having the heating plate 113 attached thereto, a nozzle 114 for injecting gas, a pressure gauge 115, and a gas discharge tube ( 118, a gas discharge valve 119, a substrate 117 is placed on the heating plate 113, and a power source of a predetermined frequency is connected between the ground electrode 111a and the working electrode 111b by the power supply unit 120. It is.

The reaction gas supply unit comprises a reaction gas cylinder 131, a reaction gas valve 132, a flow controller 133, a mixing valve 146, a valve 147, and a connection pipe connecting them to the reaction gas stored in the reaction gas cylinder 131. When the reaction gas valve 132 is opened, it is input to the flow controller 133 through a connection pipe, and after the flow of gas is controlled in the flow controller 133, the nozzle in the discharge tube via the mixing valve 146 and the valve 147. Sprayed at 114.

The carrier gas supply part includes a carrier gas cylinder 141, a carrier gas valve 142, a flow controller 143, a mixing valve 146, a valve 147, and a connection pipe connecting them to the carrier gas stored in the carrier gas cylinder 141. When the carrier gas valve 142 is opened, it is input to the flow controller 143 through a connecting pipe, and after the flow of gas is controlled in the flow controller 143, the nozzle in the discharge tube via the mixing valve 146 and the valve 147. Sprayed at 114.

The additive gas supply unit includes a barrel 150 in which a source for generating additive gas (DI water) 152 is stored, and a carrier gas cylinder 141, a valve 144, and a flow meter 145 for supplying carrier gas to the barrel 150. Consists of a connecting pipe, the barrel 150 is provided with a heat sensor 153 for sensing the temperature, the pipe into which the carrier gas flows is inserted into the source 152 to bubble the source, bubbling The added gas of the prepared source is mixed with other gases in the mixing valve 146 through the discharge pipe, the valve 154 and the flow meter 155 and injected into the discharge tube 110. At this time, the barrel 150 is provided with a heating device 151 for heating the source, the connection pipe through which the additive gas flows is provided with a heating device 156 to increase the temperature of the connection pipe.

In the first embodiment, DI water is used as the source 152, the temperature of the source 152 is maintained at 60 ° C. to 110 ° C., and the gas line is also maintained at 100 ° C. by the heating device 156.

In such a configuration, the additive gas is generated from DI water bubbled by the carrier gas, flows along the reaction gas and the carrier gas in the mixing valve 146, and is injected into the discharge tube 110 from the nozzle 114. At this time, the flow of each gas is controlled by the flow controller (133, 143, 145, 155).

When the voltage is applied to both electrodes 111a and 111b by the power supply unit 120, the discharge tube 110 discharges by the reaction gas. At this time, OH radicals are generated by the additive gas of DI water introduced together with the reaction gas. . Therefore, washing is more efficiently performed by OH radicals having strong oxidizing power, and ozone generation is suppressed.

Second embodiment

As shown in FIG. 2, the apparatus for injecting H ₂ O of 100 ° C. or higher directly into the discharge region includes a discharge tube 110, a reaction gas supply unit, a carrier gas supply unit, and a steam supply unit. In the configuration of FIG. 2, since the discharge tube 110, the reaction gas supply unit, and the carrier gas supply unit are the same as those of FIG. 1, further description will be omitted to avoid repetition. However, in FIG. 1, a pipe going to a source is required in order to bubble using a carrier gas, but in the second embodiment, the pipe is removed since the additive gas is supplied to a separate line using a boiler, and thus the heating device (FIG. 1, 156) is also unnecessary.

Referring to FIG. 2, a boiler 170 is used to generate water vapor as an additive gas, and the boiler 170 boils water 172 by the heating device 171, and the generated water vapor is connected to the connection pipe and the valve 174. Sprayed directly from the nozzle 175 via? At this time, the tube is provided with a heating device 173 for maintaining a high temperature.

That is, steam is generated while water is heated by the heater 171 of the boiler, and the steam is directly injected into the discharge tube 110 through a gas pipe separate from the pipe for injecting the reaction gas. The discharge tube 110 is discharged by the reaction gas when a voltage is applied to both electrodes (111a, 111b), at this time OH radicals are generated by the water vapor injected from a separate tube. Therefore, washing is more efficiently performed by OH radicals having strong oxidizing power, and ozone generation is suppressed.

Third embodiment

The method of using alcohol or acetone for generating an additive gas for generating OH radicals uses alcohol or acetone as a source in the configuration as shown in FIG. However, since alcohol or acetone has a high vapor pressure even at a low temperature, the heating device (151, 156 of FIG. 1) required in FIG. 1 is not required. In other words, there is no need for a separate heating device 151 in the barrel 150, and there is no need to install the heating device 156 in the pipe, which can be implemented more simply.

Since the operation of the third embodiment is also the same as the operation of the first embodiment except for the heating operation, further description is omitted to avoid repetition.

Fourth embodiment

How to use the OH radical generating peroxide to hydrogen (H ₂ O ₂₎ is used for the hydrogen peroxide (H ₂ O ₂₎ as a source in the configuration as shown in FIG. However, since the peroxide water has a high vapor pressure even at a low temperature, the heating device (151, 156 of FIG. 1) is not necessary in FIG. In other words, hydrogen peroxide is oxidizing in itself, but decomposition of hydrogen peroxide by plasma energy can produce large amounts of OH radicals, which are stronger oxidants.

Since the operation of the fourth embodiment is also the same as the operation of the first embodiment except for the heating operation, further description is omitted to avoid repetition.

On the other hand, when various sources (DI water, alcohol, acetone, hydrogen peroxide, etc.) are injected into the discharge tube 110 as an additive gas, OH groups (radical) are generated at the time of discharging, and thus, more effective cleaning or ashing is performed by the strong oxidation. In addition to this, the use of ultraviolet rays may yield more OH radicals. That is, in the case of ozone generated during discharge, OH radicals are generated by ultraviolet irradiation as shown in Equation 2 below. Therefore, the addition of a gas such as Xe, Ne, KrF having a large UV emission to the reaction gas can further promote the generation of OH radicals.

In addition, by controlling the temperature of the substrate, it is possible to further promote the oxidation reaction of the organic matter occurring on the substrate surface. For example, it is more effective if the temperature of the substrate is about 150 ° C to 250 ° C. In addition, it is preferable to form a magnetic field around the workpiece and the discharge electrode in order to lengthen the lifetime of the generated radicals. Such a magnetic field may be formed by installing a permanent magnet or winding a coil around a discharge tube.

Although not specifically illustrated in the drawings, when the silicon wafer to be processed or the glass panel to be processed reciprocates or rotates in a straight line, the processing speed or uniformity of the surface treatment may be further improved. By controlling the total flow control of, it is possible not only to chemically remove organic impurities but also to physically remove particles.

Such a technique of the present invention can be effectively applied to a flat panel display manufacturing process, semiconductor wafer cleaning process, photoresist stripping (PR) process, which is an organic material removing process, and the like.

As described above, according to the present invention, by adding a gas of water vapor, alcohol, acetone, or hydrogen peroxide to the reaction gas and injecting it into the discharge tube, OH radicals are generated by discharge, and the semiconductor substrate is effectively subjected to the strong oxidation of the OH radicals. Can be cleaned dry, and the generation of harmful ozone can be suppressed. Furthermore, Xe, Ne, KrF, etc., which are easily generated in ultraviolet rays, may be added to the reaction gas to increase the generation of OH radicals, and the temperature of the substrate may be controlled to improve the cleaning ability.

Claims (10)

In the substrate cleaning / ashing method using an atmospheric pressure plasma discharge, Inject one of the group consisting of water vapor, alcohol, acetone, and hydrogen peroxide into the discharge tube together with the reaction gas to generate OH radicals during discharge. A dry cleaning / ashing method comprising cleaning / ashing a semiconductor substrate, a glass panel, and a transparent polymer. The dry cleaning / ashing method as claimed in claim 1, wherein one of the group consisting of Xe, Ne, and KrF is added to the reaction gas to promote OH radical generation by ultraviolet radiation. The dry cleaning / ashing method according to claim 1, wherein when using the steam, the steam is generated by a boiler or by bubbling of carrier gas. The method of claim 1, wherein the substrate or glass panel is heated to about 150 ° C. to 250 ° C. to activate the reaction. The dry cleaning / ashing method as claimed in claim 1, wherein the substrate or glass panel is moved straight or reciprocated to homogenize the reaction. An atmospheric pressure plasma discharge tube capable of mounting a substrate for cleaning / ashing, and generating plasma by discharge when a predetermined voltage is applied to both electrodes having a dielectric therebetween; Reaction gas injection means for injecting reaction gas into the atmospheric pressure plasma discharge tube; Carrier gas injection means for injecting a carrier gas for transporting gases into the atmospheric pressure plasma discharge tube; And Dry cleaning / ashing apparatus, characterized in that consisting of additional gas injection means for injecting the additional gas into the plasma discharge tube. 7. The dry cleaning / ashing apparatus according to claim 6, wherein the additive gas injection means is configured to bubble and inject any one of DI water, acetone, alcohol, and hydrogen peroxide using the carrier gas. The dry cleaning / ashing apparatus according to claim 6, wherein the additive gas injection means is configured to directly inject steam of boiling water into the atmospheric plasma discharge tube by a boiler. The dry cleaning / ashing device according to claim 6, wherein the atmospheric plasma discharge tube further comprises a heating device for heating the substrate or the glass panel. The dry cleaning / ashing device according to claim 6, wherein the atmospheric pressure plasma discharge tube is formed with a magnet or a coil for generating a magnetic field.